Question

in the spectrophotometry lab experiment, you calibrated a spectrophotometer and measured the absorbance of different dye samples. after identifying the analytical wavelength of a dye and measure the absorbance of five dye samples of varying concentrations. then, you will construct a calibration curve and use it to determine the molar absorptivity,, of your dye. using your calibration curve, you will also calculate the concentration of an unknown based on the experiement, select the incorrect statement below:
the amount of light absorbed at different wavelengths by a sample can be measured with an instrument called a spectrophotometer.
the analytical wavelength, λ max, is the wavelength where the largest amount of light is absorbed by the sample and that has the highest molar absorptivity, ε.
the absorbance of a substance varies with wavelength and concentration.
solutions with higher concentrations have lower absorbances, while more dilute solutions have higher absorbances.

Explanation:

• Let's analyze each option:
• Option 1: A spectrophotometer measures light absorption at different wavelengths. This is correct.
• Option 2: $\lambda_{max}$ is the wavelength with maximum light absorption and highest molar absorptivity. This is correct.
• Option 3: Absorbance ($A$) is related to concentration ($c$) and path length ($b$) by Beer's Law ($A = \epsilon bc$), so it varies with both wavelength (since $\epsilon$ can vary with $\lambda$) and concentration. This is correct.
• Option 4: According to Beer's Law, absorbance is directly proportional to concentration (for a given wavelength and path length). So higher concentration solutions should have higher absorbances, and more dilute solutions should have lower absorbances. This statement is incorrect.

Answer:

Solutions with higher concentrations have lower absorbances, while more dilute solutions have higher absorbances.